The Cygnal survey showed Braun leading Donnelly 49-to-46 percent in a critical campaign to determine which party will control the upper chamber for the next two years. More than seven out of 10 Indiana voters rated their interest in the midterms as 9 or 10 on a scale from 1 to 10, and nearly 20 percent had already voted.

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The poll tracks with other recent surveys that have shown Braun with a small advantage over Donnelly. The latest RealClearPolitics average before the Cygnal poll gave Braun a 0.5 point lead.

Further good news for Republicans from the poll includes President Donald Trump holding a 53 percent favorability rating in the state, with 45 percent viewing him unfavorably. That +8 number is significantly higher than his national approval ratings, which have been consistently underwater.

"There are those who want to send the president a message, but that is not translating into significant votes for Donnelly," said Josh Pendergrass, Cygnal’s director of client strategy, in a release. "Voters are more likely to support candidates who support President Trump than they are to support candidates who oppose him. Republicans have a real chance of flipping the Indiana Senate seat when Trump supporters turn out."

Donnelly is one of several Senate Democrats battling for re-election in states Trump won handily in 2016—he carried Indiana by nearly 20 points over Democrat Hillary Clinton.

Braun, a businessman who served in the state legislature, recently told the Washington Free Beacon he felt momentum swinging in his favor when Donnelly voted against Supreme Court Justice Brett Kavanaugh's confirmation, after supporting Trump's first nominee, Neil Gorsuch.

"We could track it from the moment Donnelly said he was going to vote against Kavanaugh, small contributions increased at a rate of three to four times what they were before," he said.

David Rutz is managing editor of the Washington Free Beacon. He was previously a sports reporter for two years in Atlanta and has done freelance sports reporting for the Washington Post. He graduated from Vanderbilt University in 2010 and lives in Marietta, Ga. His Twitter handle is @DavidRutz.